Forlan and Argentine partner Federico Coria went down in straight sets against Bolivian duo Boris Arias and Federico Zeballos after receiving a wildcard entry for ATP Challenger event the Uruguay Open in Montevideo.
Both teams held serve to start the match, but Arias and Zeballos quickly pulled away after earning a break in the third game of the first set.
The second set followed in similar fashion, with Forlan and Coria struggling to contain the high-powered serving of their opponents.
The Bolivian pair won 85 per cent of their first serves for the match as they clinched the win in just 47 minutes.
Forlan signed for Manchester United from Argentinian club Independiente in 2002 and was part of Sir Alex Ferguson’s squad which won the 2003 Premier League title and the 2004 FA Cup.
After making 98 appearances, scoring 17 goals, Forlan joined Spanish side Villarreal and later played for Atletico Madrid as well as Inter Milan before spells in Brazil, Japan, Uruguay, India and Hong Kong.
He scored 36 goals in 112 appearances for his country, finishing as joint top goalscorer at the 2010 World Cup as Uruguay secured a third-place finish in South Africa, and won the 2011 Copa America.
Forlan was a promising junior tennis player and has continued to play since hanging up his boots in 2019.